Science & Technology
Computers and Information Technology
Computer Basics: Hardware, Software and Emerging Technologies
Computer generations, CPU, memory, storage units, input-output devices, software, languages, number systems, Indian supercomputers and new tech for CGPSC.
Prerequisites
- No technical background is needed. Class 10 science vocabulary is enough.
- Computers and Information Technology: chapter overview shows how this page leads into the internet and e-governance pages.
- Physics in Everyday Life helps with the electricity and light ideas behind chips, hard disks and optical discs.
The Hook: The Answer Sheet You Will Fill
Connect
On the day of CGPSC Prelims you will darken circles on an OMR sheet. A few weeks later a machine reads lakhs of sheets in a few hours, a computer compares each with the answer key, applies the one-third negative marking and prints a merit list. The same week, a patwari in your village prints a land record from the Bhuiyan portal and a ration shop in Bastar weighs grain on a machine that checks your thumbprint.
Every one of these is a computer doing four things: input, processing, storage and output. What are its parts, how does it store a mark or a thumbprint as 0s and 1s, and where is computing heading next? This page answers those questions.
Why it matters: Prelims asks one-line facts (“Which memory is volatile?”, “Who is called the father of the computer?”, “1 byte = ? bits”). Mains P-IV (GS-II) asks short notes on supercomputers, AI, cloud computing and the role of computers in development.
What a Computer Is
A computer (संगणक) is an electronic machine that accepts data (input), processes it according to a set of instructions (program), stores it and produces results (output). The cycle is often called IPO (Input–Process–Output), with storage alongside.
graph LR
A["Input
keyboard, scanner,
biometric reader"] --> B["CPU
ALU + Control Unit
+ registers"]
B --> C["Output
monitor, printer,
speaker"]
B <--> D["Memory
cache, RAM, ROM"]
D <--> E["Storage
HDD, SSD, pen drive"]Milestones in computing
| Person / machine | Contribution |
|---|---|
| Charles Babbage | Designed the Difference Engine and the Analytical Engine (19th century). The Analytical Engine had a “mill” (processor) and a “store” (memory), so Babbage is called the “father of the computer” |
| Ada Lovelace | Wrote an algorithm for the Analytical Engine; often called the first computer programmer |
| Alan Turing | Described the “Turing machine” (1936), the theoretical model of all computers; proposed the Turing Test for machine intelligence (1950) |
| ENIAC | Early general-purpose electronic digital computer, built in the USA in the mid-1940s (unveiled 1946); used vacuum tubes |
| Transistor | Invented at Bell Labs in 1947 (Bardeen, Brattain, Shockley) |
| Integrated circuit (IC) | Jack Kilby (1958) and Robert Noyce (1959), working independently |
| Microprocessor | Intel 4004 (1971): a whole CPU on one chip |
Generations of computers
Dates differ slightly between textbooks. Learn the technology of each generation, which is what MCQs test.
| Generation | Core technology | Typical features |
|---|---|---|
| First (1940s–1950s) | Vacuum tubes | Huge, hot, power-hungry; machine language; punched cards (ENIAC, UNIVAC) |
| Second (late 1950s–1960s) | Transistors | Smaller, more reliable; assembly language and early high-level languages (FORTRAN, COBOL) |
| Third (1960s–1970s) | Integrated circuits | Keyboards and monitors; operating systems; multiprogramming |
| Fourth (1970s–present) | Microprocessors (LSI/VLSI chips) | Personal computers, laptops, networks, the internet |
| Fifth (present and future) | Artificial intelligence, parallel processing, ULSI | Natural-language interfaces, machine learning, robotics |
Types of computers
| By working principle | By size and power |
|---|---|
| Analog: works on continuous quantities (old speedometer, thermometer-type devices) | Microcomputer: personal computers, laptops, smartphones |
| Digital: works on discrete values (0 and 1); almost all modern computers | Minicomputer: mid-range multi-user systems |
| Hybrid: combines both, e.g. medical equipment such as ICU monitors that convert analog signals to digital | Mainframe: large organisations handling bulk transactions (banks, railways reservation) |
| Supercomputer: fastest class; weather forecasting, climate models, nuclear and drug research |
Hardware (हार्डवेयर)
The CPU: the brain
The Central Processing Unit (केंद्रीय प्रसंस्करण इकाई) has three parts:
| Part | Job |
|---|---|
| ALU (Arithmetic Logic Unit) | Calculations (+, −, ×, ÷) and logical comparisons (greater than, equal to, AND, OR) |
| CU (Control Unit) | Fetches instructions, decodes them and directs the other parts; does not process data itself |
| Registers | Tiny, fastest storage inside the CPU for the data being worked on right now |
Processor speed is measured in hertz (clock cycles per second), today usually in GHz. A multi-core processor has several processing units on one chip. A GPU (Graphics Processing Unit) has thousands of small cores that do many simple calculations in parallel, which is why GPUs now power AI training.
Memory hierarchy
Fastest and costliest at the top, slowest and cheapest at the bottom:
| Level | Type | Key fact |
|---|---|---|
| 1 | Registers | Inside the CPU |
| 2 | Cache memory | Very fast buffer between CPU and RAM; made of SRAM |
| 3 | Primary memory: RAM | Volatile (data lost when power goes off); working memory for running programs. Main memory uses DRAM, which must be refreshed constantly |
| 3 | Primary memory: ROM | Non-volatile; holds start-up instructions (BIOS/firmware) |
| 4 | Secondary storage | Non-volatile, large: HDD (magnetic), SSD and pen drives (flash), optical discs |
Kinds of ROM: PROM (programmed once), EPROM (erased with ultraviolet light), EEPROM (erased electrically). Flash memory, used in pen drives, SSDs and phones, is a fast type of EEPROM.
Virtual memory: when RAM fills up, the operating system uses part of the hard disk or SSD as if it were RAM. It is slower than real RAM.
Optical discs
| Disc | Typical capacity (single layer) | Laser |
|---|---|---|
| CD | About 700 MB | Infrared |
| DVD | 4.7 GB | Red |
| Blu-ray | 25 GB | Blue-violet (shorter wavelength, so smaller pits and more data) |
Units of data
| Unit | Equals |
|---|---|
| Bit (binary digit) | 0 or 1, the smallest unit |
| Nibble | 4 bits |
| Byte | 8 bits (enough for one English character) |
| Kilobyte (KB) | 1,024 bytes |
| Megabyte (MB) | 1,024 KB |
| Gigabyte (GB) | 1,024 MB |
| Terabyte (TB) | 1,024 GB |
| Then | Petabyte (PB) → Exabyte (EB) → Zettabyte (ZB) → Yottabyte (YB) |
1,000 or 1,024?
Computer memory uses powers of 2, so the traditional answer is 1 KB = 1,024 bytes (\(2^{10}\)). Disk makers and the SI system use 1 kB = 1,000 bytes, and the strict binary unit is written KiB (kibibyte). In an exam, choose 1,024 unless the question says otherwise.
Input and output devices
| Input devices | Output devices |
|---|---|
| Keyboard, mouse, joystick, microphone, webcam | Monitor (LED/LCD), speaker, headphones |
| Scanner; OCR (Optical Character Recognition: reads printed text) | Printers: impact (dot-matrix, prints through a ribbon) and non-impact (inkjet, laser) |
| OMR (Optical Mark Recognition: reads darkened circles on answer sheets) | Plotter: large drawings, maps, engineering designs |
| MICR (Magnetic Ink Character Recognition: the code line at the bottom of bank cheques) | Projector |
| Barcode reader, QR code scanner, RFID reader (FASTag) | |
| Biometric devices: fingerprint, iris and face scanners (Aadhaar authentication) |
A touchscreen is both an input and an output device.
Software (सॉफ्टवेयर)
| Type | What it does | Examples |
|---|---|---|
| System software | Runs the hardware and gives a platform for other programs | Operating system, device drivers, utilities (antivirus, disk cleanup) |
| Application software | Does a task for the user | Word processor, spreadsheet, browser, UPI app |
| Firmware | Software permanently stored in ROM of a device | BIOS, software inside a washing machine |
Operating system (ऑपरेटिंग सिस्टम): manages memory, processes, files, devices and security, and gives the user an interface (command-line or graphical). Examples: Windows, macOS, Linux (kernel by Linus Torvalds, 1991), Android (based on the Linux kernel), iOS. India’s BOSS Linux (Bharat Operating System Solutions) was developed by C-DAC.
| Licence model | Meaning |
|---|---|
| Open-source | Source code available to read, change and share (Linux, LibreOffice) |
| Proprietary | Code owned by a company; use under licence (Windows, MS Office) |
| Freeware | Free to use, code not necessarily open |
| Shareware | Free trial, pay to keep using |
Programming languages
| Level | Example | Translator |
|---|---|---|
| Machine language | Binary 0s and 1s; the only language the CPU understands directly | None needed |
| Assembly language | Short codes (mnemonics) such as ADD, MOV | Assembler |
| High-level language | FORTRAN (scientific, 1950s), COBOL (business), C (Dennis Ritchie, 1972), Java (1995), Python (1991) | Compiler or interpreter |
- A compiler translates the whole program at once into machine code, then it runs (C, C++).
- An interpreter translates and runs line by line, stopping at the first error (Python is usually run this way).
Number Systems and Codes
| System | Base | Digits used |
|---|---|---|
| Binary | 2 | 0, 1 |
| Octal | 8 | 0–7 |
| Decimal | 10 | 0–9 |
| Hexadecimal | 16 | 0–9 and A–F (A = 10 … F = 15) |
Decimal to binary: divide by 2 repeatedly and read the remainders from bottom to top. Example: 13 → 13 ÷ 2 = 6 r 1, 6 ÷ 2 = 3 r 0, 3 ÷ 2 = 1 r 1, 1 ÷ 2 = 0 r 1 → 1101.
Check: \(1\times 8 + 1\times 4 + 0\times 2 + 1\times 1 = 13\).
| Code | Fact |
|---|---|
| ASCII | 7-bit code: 128 characters (English letters, digits, symbols) |
| Unicode | Covers almost every script in the world, including Devanagari; this is why Hindi and Chhattisgarhi text works on phones and government portals |
Logic gates are the building blocks of digital circuits: AND, OR, NOT, and the “universal gates” NAND and NOR (any circuit can be built from either one alone).
Supercomputers and India
- A supercomputer’s speed is measured in FLOPS (floating-point operations per second): teraflops (\(10^{12}\)), petaflops (\(10^{15}\)), exaflops (\(10^{18}\)). The world ranking is the TOP500 list, published twice a year.
- C-DAC (Centre for Development of Advanced Computing), Pune, was set up in 1988 after India was denied the import of a supercomputer.
- PARAM 8000 (1991) was India’s first indigenous supercomputer, built by C-DAC under Vijay Bhatkar. “Param” (परम) means “supreme”.
- National Supercomputing Mission (NSM), 2015: a joint mission of MeitY and the Department of Science and Technology, implemented by C-DAC and the Indian Institute of Science (IISc), Bengaluru, to build a grid of supercomputers in academic and research institutions under the PARAM series.
- Uses in India: monsoon and cyclone forecasting (the IMD and the Ministry of Earth Sciences run their own high-performance computers), drug discovery, oil exploration, climate studies and AI training.
Emerging Technologies (Mains Favourites)
| Technology | In one line | India’s policy hook (dated) |
|---|---|---|
| Artificial Intelligence (AI) (कृत्रिम बुद्धिमत्ता) | Machines that learn from data to recognise speech, images and patterns and to make predictions. Machine learning is the main approach; generative AI creates text, images and code | IndiaAI Mission approved March 2024 (outlay about ₹10,372 crore) for compute capacity, datasets and Indian foundation models |
| Quantum computing | Uses qubits, which can be in superposition of 0 and 1 and can be entangled; promises huge speed-ups for some problems (cryptography, materials, drug design) | National Quantum Mission approved April 2023, about ₹6,003.65 crore for 2023-24 to 2030-31 |
| Cloud computing | Renting computing power and storage over the internet. Service models: IaaS (infrastructure), PaaS (platform), SaaS (software) | Government cloud MeghRaj (GI Cloud) |
| Internet of Things (IoT) | Everyday objects with sensors connected to the internet: smart meters, soil-moisture sensors, FASTag | Smart Cities, smart electricity meters |
| Blockchain | A shared, tamper-evident digital ledger kept on many computers at once | Used for land-record and certificate pilots |
| Big data and analytics | Analysing very large datasets for patterns | Targeting welfare schemes, tax analytics |
| Semiconductors | Chips are the base of all IT; India imports most of them | India Semiconductor Mission (December 2021, ₹76,000 crore incentive programme) |
Moore’s Law (Gordon Moore, 1965, revised 1975): the number of transistors on a chip doubles about every two years. It explains why computers became cheap enough to reach every village, though the trend has slowed as transistors approach atomic sizes.
Mains angle: AI and governance
For an answer on AI, balance opportunities (crop-disease detection from phone photos, Indian-language translation through Bhashini, early disease screening, fraud detection in welfare schemes) with concerns (job displacement, bias in data, deepfakes and misinformation, privacy, the cost of computing power, and concentration in a few companies). End with “responsible AI”: human oversight, transparency, data protection under the DPDP Act, 2023, and Indian-language datasets. See Internet and Communication for the law.
Memory Tricks
Generations: 'Very Tired Indians Make AI'
Vacuum tubes → Transistors → Integrated circuits → Microprocessors → AI.
RAM vs ROM
RAM = Rough work that is wiped when the light goes off (volatile).
ROM = Rules Of the Machine, written in permanently (non-volatile).
The three readers
- OMR = Marks (exam sheets).
- OCR = Characters (printed text).
- MICR = Magnetic ink on cheques (banks).
Don’t Confuse
| This | vs | That |
|---|---|---|
| Compiler: whole program at once | vs | Interpreter: line by line |
| Cache: SRAM, very fast, small | vs | Main RAM: DRAM, slower, larger |
| EPROM: erased by UV light | vs | EEPROM / flash: erased electrically |
| Control Unit: directs, does not compute | vs | ALU: does the calculating and comparing |
| Hardware: physical parts | vs | Firmware: software stored permanently in hardware |
| Bit: 0 or 1 | vs | Byte: 8 bits |
| PARAM 8000 (1991): first Indian supercomputer | vs | NSM (2015): mission to build a supercomputer grid |
Common Mistakes
MCQ traps
- “ROM is volatile.” False. RAM is volatile. ROM keeps its contents without power.
- “Cache memory is part of secondary storage.” False. Cache sits between the CPU and RAM and is the fastest memory after registers.
- “The Control Unit performs arithmetic.” False. The ALU does arithmetic and logic; the CU controls the flow.
- “MICR is used in OMR answer sheets.” False. MICR reads the magnetic-ink code on cheques.
- “A nibble is 8 bits.” False. A nibble is 4 bits; a byte is 8.
- “Charles Babbage built the first electronic computer.” False. Babbage designed mechanical engines in the 19th century; electronic computers came in the 1940s.
Practice
All questions below are original practice questions written in CGPSC style. They are not previous-year questions.
Level 1: Foundation
- 1 byte = ______ bits, and 1 nibble = ______ bits.
- The part of the CPU that performs arithmetic and logical operations is the ______.
- India’s first indigenous supercomputer, built by C-DAC in 1991, was ______.
- Convert decimal 25 to binary.
Answers
- 8 bits; 4 bits.
- ALU (Arithmetic Logic Unit).
- PARAM 8000.
- 25 → 12 r 1, 6 r 0, 3 r 0, 1 r 1, 0 r 1 → read upwards: 11001 (16 + 8 + 1 = 25).
Level 2: Prelims MCQs
Q1. Consider the following statements:
- RAM is a volatile memory, while ROM is non-volatile.
- Cache memory is slower than the main memory but larger in size.
- EPROM can be erased by exposing it to ultraviolet light.
Which of the statements given above is/are correct?
- (a) 1 only
- (b) 1 and 3 only
- (c) 2 and 3 only
- (d) 1, 2 and 3
Answer and explanation
(b) 1 and 3 only. RAM loses its contents when power goes off; ROM does not. Statement 2 is reversed: cache is faster and smaller than main memory, which is the whole point of a cache. EPROM (Erasable Programmable ROM) is wiped with UV light, unlike EEPROM, which is erased electrically.
Q2. Match List I (Device or technology) with List II (Typical use):
| List I | List II |
|---|---|
| A. MICR | 1. Reading darkened circles on examination answer sheets |
| B. OMR | 2. Reading the code line printed on bank cheques |
| C. OCR | 3. Converting printed text into editable text |
| D. RFID | 4. Electronic toll collection through FASTag |
- (a) A-2, B-1, C-3, D-4
- (b) A-1, B-2, C-3, D-4
- (c) A-2, B-3, C-1, D-4
- (d) A-3, B-1, C-2, D-4
Answer and explanation
(a) A-2, B-1, C-3, D-4. MICR reads magnetic-ink characters on cheques. OMR detects marks on answer sheets. OCR recognises printed characters. FASTag is a passive RFID tag read by readers at toll plazas.
Q3. Which one of the following is the correct sequence of the core technology used in successive generations of computers?
- (a) Transistors → Vacuum tubes → Integrated circuits → Microprocessors
- (b) Vacuum tubes → Integrated circuits → Transistors → Microprocessors
- (c) Vacuum tubes → Transistors → Integrated circuits → Microprocessors
- (d) Vacuum tubes → Transistors → Microprocessors → Integrated circuits
Answer and explanation
(c). First generation: vacuum tubes; second: transistors; third: integrated circuits; fourth: microprocessors (a full CPU on a VLSI chip, from the Intel 4004 in 1971). The fifth generation is associated with AI and parallel processing.
Q4. With reference to India’s computing initiatives, which of the following statements is correct?
- (a) The National Supercomputing Mission is implemented by ISRO and DRDO.
- (b) PARAM 8000 was developed by C-DAC and is regarded as India’s first indigenous supercomputer.
- (c) The National Quantum Mission was launched along with Digital India in 2015.
- (d) BOSS Linux is a proprietary operating system developed by a private company.
Answer and explanation
(b). C-DAC (set up in 1988) built PARAM 8000 in 1991. NSM (2015) is a MeitY–DST mission implemented by C-DAC and IISc Bengaluru, so (a) is wrong. The National Quantum Mission was approved in April 2023, so (c) is wrong. BOSS (Bharat Operating System Solutions) is an open-source Linux distribution from C-DAC, so (d) is wrong.
Q5. A program is translated and executed one line at a time, and execution stops at the first error. The translator used is a/an:
- (a) Compiler
- (b) Assembler
- (c) Interpreter
- (d) Loader
Answer and explanation
(c) Interpreter. A compiler translates the whole program before it runs. An assembler converts assembly language (mnemonics) into machine code. A loader places a program in memory for execution.
Level 3: Mains Answer Writing
Q1. (60 words) Distinguish between RAM and ROM.
Model answer outline
- RAM (Random Access Memory): volatile; read and write; holds the programs and data currently in use; larger; types SRAM (cache) and DRAM (main memory).
- ROM (Read Only Memory): non-volatile; mainly read; holds firmware and start-up instructions (BIOS); smaller; types PROM, EPROM, EEPROM.
- One line: RAM is the computer’s working desk; ROM is its permanent rule book.
Q2. (150–200 words) What is Artificial Intelligence? Discuss its potential and risks for a developing state like Chhattisgarh.
Model answer outline
- Intro: AI is the ability of machines to perform tasks that normally need human intelligence, such as recognising images and speech, translating and predicting, mainly through machine learning on large data.
- Potential:
- Agriculture: pest and disease detection from phone photos for paddy farmers; weather and price advisories.
- Health: screening (for example, reading X-rays) where specialists are scarce, as in remote Bastar and Surguja blocks.
- Governance: detecting duplicate beneficiaries in PDS and pensions; grievance analysis.
- Language: translation and voice interfaces in Hindi, Chhattisgarhi and tribal languages (Bhashini).
- Forests and minerals: satellite and drone data to track forest fires and illegal mining.
- Risks: job loss in routine work; biased data excluding tribal and poor users; deepfakes; privacy; dependence on costly computing and foreign platforms; the rural digital divide.
- Way forward: IndiaAI Mission (2024) compute and datasets; DPDP Act, 2023 safeguards; skilling; local-language datasets; human oversight in welfare decisions.
- Conclusion: AI can be a force-multiplier for an under-served state if it is inclusive, explainable and accountable.
Quick Revision Table
| Fact | Detail |
|---|---|
| Father of the computer | Charles Babbage (Analytical Engine) |
| First programmer | Ada Lovelace |
| Generations | Vacuum tubes → transistors → ICs → microprocessors → AI |
| First microprocessor | Intel 4004 (1971) |
| CPU parts | ALU, Control Unit, registers |
| Volatile memory | RAM (SRAM = cache, DRAM = main memory) |
| Non-volatile | ROM, PROM, EPROM (UV), EEPROM, flash |
| Byte / nibble | 8 bits / 4 bits |
| 1 KB | 1,024 bytes (binary convention) |
| Blu-ray | Blue-violet laser, 25 GB single layer |
| MICR / OMR / OCR | Cheques / answer sheets / printed text |
| Compiler vs interpreter | Whole program vs line by line |
| Universal gates | NAND, NOR |
| Unicode | Supports Devanagari and nearly all scripts |
| C-DAC | Pune, 1988 |
| PARAM 8000 | 1991; first Indian supercomputer (Vijay Bhatkar) |
| NSM | 2015; MeitY + DST; C-DAC and IISc |
| National Quantum Mission | Approved April 2023; about ₹6,003.65 crore to 2030-31 |
| IndiaAI Mission | Approved March 2024; about ₹10,372 crore |
| India Semiconductor Mission | December 2021; ₹76,000 crore programme |
Key Takeaways
Key Takeaways
- A computer is an input–process–storage–output machine; the CPU is the ALU plus the Control Unit plus registers.
- Memory runs from registers and cache (fastest) to RAM, ROM and secondary storage; RAM is volatile.
- Generations follow technology: vacuum tubes, transistors, ICs, microprocessors, AI.
- Everything is stored in binary; Unicode is what lets Devanagari appear on screens.
- India’s computing story runs from C-DAC and PARAM (1988–1991) to NSM (2015), the Quantum Mission (2023) and the IndiaAI Mission (2024). Mains wants both the potential and the risks.
What’s Next
- Internet and Communication: how computers talk to each other, from optical fibre to 5G, and how cyber law protects users
- Digital India, E-Governance and IT in Rural India: computers put to work for citizens
- Space and Defence Technology: satellites and the computing behind them
- Computers and IT: Quick Revision: the chapter on one page
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